Throughout the span of the average individual's life they may through some means lose a tooth. The loss of a tooth may come by many different means such as an accident or decay. The loss of a tooth creates a gap which, on anterior surfaces, may seem aesthetically unpleasant and on a posterior tooth the loss of a chewing surface. The loss of more than one tooth will only exacerbate these problems. Once the tooth is ultimately lost the bone surrounding the tooth begins to deteriorate to the eventual loss of the socket. This creates a number of problems in creating a compatible prosthetic that is capable of replacing a lost tooth. The need for such a replacement tooth brought about the invention of the dental implant.
The dental implant is a device that by design is intended to replace the function of a lost tooth. Commercially available dental implants usually have the following characteristics:
a. Biocompatibility—the material that the implant is made from must be biocompatible. Many materials are not compatible with long-term implantation and are eventually rejected by the body. Therefore, the materials of choice are those that are the most inert—commercially available dental implants have settled upon the metal titanium as the material of choice. Since titanium forms an oxide coating that protects it from further rusting, it is ideal. Other noble metals such as platinum and gold would also be inert, but cost and physical properties would limit their use. Titanium is a good balance between inertness, physical properties, and cost, and is therefore the material most often used.
b. Physical Properties—the material must exhibit sufficient strength and toughness in order to withstand the biting forces present during routine use. A weak biocompatible dental implant would simply break under the constant impact present while biting or chewing. The implant must be durable in that it must survive the constant impact and grinding forces of the teeth over the lifetime of the patient.
Dental implants are usually designed with two pieces. The first one being the post implant and the second being the prosthetic itself. Post implants are designed to be fitted or screwed into the bone, as they are the anchors for the prosthetic. The clinician will usually drill a pilot hole into the bone prior to the insertion of the implant. The implant is then fitted or screwed into the pilot hole and allowed to heal before attaching the finished prosthetic. A clinician has options with respect to bone preparation; in some cases there might be insufficient bone with which to place an implant, therefore the clinician can place artificial bone under the tissue and grow bone if necessary. A clinician can choose the size and type of implant to best fit the patient's needs—if the patient has little bone into which to place an implant a clinician can choose a smaller implant. Though of course there is a trade off with regards to the size of the implant such that smaller implants will be able to withstand less force than a larger diameter implant. Also, the retention of smaller diameter posts within the bone becomes less as the diameter decreases. Therefore, the clinician must carefully choose the correct implant based upon the condition of the patient.
At the end of the post is an abutment or collar to which the prosthetic is attached. The prosthetic is usually created in a lab and usually contains a metal attachment core with a ceramic surface that by design is made to look like a tooth. The finished prosthetic is snapped or connected to the implanted post and the patient at this point has a replacement tooth that is visibly and physically existent.
As to the detailed physical properties of the post implant the intellectual community is divided into two camps. One camp is of the belief that a hard rigid post is superior to a flexible post. The belief being that a rigid post will reinforce the implant and also be more resistant to breakage since it does not undergo repeated flexing. The flexible post implant is argued by some to be superior as it is able to yield under unusual stress and resists being torn out of the socket. There is a need for dental implants whose physical properties can be adjusted for the specific needs of both camps. Metals such as titanium, whose only malleability properties are rigid, cannot fulfill these needs.
The devices and materials of the present invention comprise the use of polymers whose physical properties can be adjusted to precise specifications. These devices comprise both flexible and rigid structures such that unique and custom implants can be produced. The adaptability and flexibility of polymers also allows for improved implant designs where metals would be completely incompatible.
Instead of metals, the devices of the present invention comprise polymers, especially those polymers with exceptional physical properties and inertness. Polymers have advantages over metals in that they have the ability to flex and return to its original shape intact, whereas a metal will usually bend in similar circumstances. Metals are also limited in their method of manufacture in that they must be cast at high temperatures or each piece machined from a block. Polymers on the other hand can be molded at much lower temperatures and in machines that makes their mass production simple. Polymers have the advantage of being able to be compression, injection, blow, or thermoset molded and are generally amenable to other means of molding. Titanium implants are very expensive in part because their manufacture is difficult—e.g., the metal is expensive and the individual milling of each implant is time consuming and costly. The present invention comprises the use of the polymers as a means to create an effective, competitive post at much lower cost and requiring less intensive manual labor.